to get the gold sword you have to first beat the 6th level.after you beat the 6th level go 

to the seventh level and go insidethen go to the bomb shop in the dark world and you will 

see a super bombbuy it. it will start following you(NOTE: do not jump off any ledges)with 

the super bomb in tow go to the pyramid and go to the big wall with a crack in it and 

drop the bomb in front of the wall.  inside there will be a pond go up to it and throw your 

sword in. when the fairy appears tell her you threw it in